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BUG: KCSAN: data-race in mb_free_blocks / mb_update_avg_fragment_size

write to 0xffff888100468198 of 4 bytes by task 5476 on cpu 1:
 mb_free_blocks+0x323/0xb40 fs/ext4/mballoc.c:1833
 ext4_free_blocks+0x1418/0x1b50 fs/ext4/mballoc.c:5989
 ext4_remove_blocks+0x61a/0x800 fs/ext4/extents.c:2502
 ext4_ext_rm_leaf+0x670/0xd20 fs/ext4/extents.c:2668
 ext4_ext_remove_space+0x901/0x1300 fs/ext4/extents.c:2916
 ext4_ext_truncate+0xfe/0x170 fs/ext4/extents.c:4377
 ext4_truncate+0x76e/0xa80 fs/ext4/inode.c:4261
 ext4_evict_inode+0xa54/0xdb0 fs/ext4/inode.c:288
 evict+0x1c8/0x3c0 fs/inode.c:586
 iput_final fs/inode.c:1662 [inline]
 iput+0x430/0x580 fs/inode.c:1688
 do_unlinkat+0x2a4/0x520 fs/namei.c:4143
 __do_sys_unlink fs/namei.c:4184 [inline]
 __se_sys_unlink fs/namei.c:4182 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:4182
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888100468198 of 4 bytes by task 30010 on cpu 0:
 ext4_mb_avg_fragment_size_cmp fs/ext4/mballoc.c:834 [inline]
 ext4_mb_rb_insert fs/ext4/mballoc.c:811 [inline]
 mb_update_avg_fragment_size+0x161/0x260 fs/ext4/mballoc.c:859
 mb_mark_used+0xae0/0xc50 fs/ext4/mballoc.c:1994
 ext4_mb_use_best_found+0x102/0x320 fs/ext4/mballoc.c:2015
 ext4_mb_simple_scan_group+0x253/0x3a0 fs/ext4/mballoc.c:2293
 ext4_mb_regular_allocator+0x1974/0x2520 fs/ext4/mballoc.c:2755
 ext4_mb_new_blocks+0x762/0x1f90 fs/ext4/mballoc.c:5515
 ext4_ext_map_blocks+0x1569/0x1f00 fs/ext4/extents.c:4245
 ext4_map_blocks+0x70d/0xef0 fs/ext4/inode.c:638
 ext4_alloc_file_blocks+0x271/0x720 fs/ext4/extents.c:4432
 ext4_fallocate+0x2a7/0x4d0 fs/ext4/extents.c:4713
 vfs_fallocate+0x459/0x6a0 fs/open.c:307
 ksys_fallocate fs/open.c:330 [inline]
 __do_sys_fallocate fs/open.c:338 [inline]
 __se_sys_fallocate fs/open.c:336 [inline]
 __x64_sys_fallocate+0x75/0xc0 fs/open.c:336
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000002 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30010 Comm: syz-executor.1 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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